This invention relates to an electroplating apparatus, and more particularly to an electroplating apparatus of the continuous traveling type for electroplating a thin sheet such as a substrate for printed wiring or the like.
Recently, copper electroplating has been widely carried out on a substrate for printed wiring (hereinafter referred to as "substrate"). A conventional electroplating apparatus for such copper electroplating is constructed in such a manner that a substrate acting as a cathode is immersed in an electroplating solution received in an electroplating tank in which a soluble copper anode means is arranged. Then, the electroplating apparatus is turned on, resulting in copper electroplating being carried out on the substrate.
However, the conventional electroplating apparatus requires to successively replenish the copper anode means, because it is gradually consumed due to electrochemical dissolution with advance of the electroplating. Unfortunately, such replenishment is highly troublesome and dangerous to an operator.
Also, copper plates used for the copper anode means in the conventional electroplating apparatus is limited to a predetermined size, therefore, it is substantially impossible to vary an area of the anode means depending on a size of a substrate to be electroplated. Thus, an increase in area of the anode means relative to that of the substrate causes a thickness of a film electroplated on a peripheral portion of the substrate to be excessively increased and that at a central region thereof to be excessively decreased. This leads to a failure in formation of a film having a satisfactory uniform thickness which is required on the substrate, resulting in failing to provide the substrate with satisfactory quality.